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Wan B, Man Z, Li KC, Swain MV, Li Q. On elastoplastic behavior of porous enamel-An indentation and numerical study. Acta Biomater 2024:S1742-7061(24)00277-0. [PMID: 38801871 DOI: 10.1016/j.actbio.2024.05.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 05/16/2024] [Accepted: 05/22/2024] [Indexed: 05/29/2024]
Abstract
The micro/nano pores in natural mineralized tissues can, to a certain extent, affect their responses to mechanical loading but are generally ignored in existing indentation analysis. In this study, we first examined the void volume fraction of sound and caries lesion enamels through micro-computed tomography (micro-CT). A Berkovich indentation study was then carried out to characterize the effect of porous microstructure on the mechanical behavior of the human enamels. The indentation tests were also modeled using the nonlinear finite element analysis technique to simulate indentation load-displacement curves, which showed reasonable agreement with the experimental measurements. From the simulation results, the extent of densification in the plastic zone was identified and the corresponding stress and contact pressure evolutions were quantified. Further, a conventional elastic-perfectly plastic material model without considering micropores was also developed to investigate the compaction effect of the porous structure. The simulation results reveal that conventional elastic perfect-plastic constitutive models become less reliable to model the mechanical behavior of carious lesion enamel with increasing loss of mineral content as it underestimates the yield stress and plastic energy dissipation. This study divulges the importance of compaction of porous enamel structure beneath the indented area. Note that understanding the effect of porous microstructures on plastic behavior is vital as the involved inelastic deformation mechanism associated with irreversible processes, such as wear and localized microcracking, has a significant bearing on wear and fatigue behavior of enamel. STATEMENT OF SIGNIFICANCE: Based on micro-CT and nano-indentation characterization, a numerical model was developed aiming to precisely describe the deformation behavior of naturally porous enamel. Inelastic properties and energy dissipation characteristics of porous enamel were investigated in detail. This work demonstrated that the existence of micro-pores in White Spot Lesions (WSLs) contributes to mechanical stability, which can mitigate the reduction in Young's modulus and fracture toughness resulting from loss of mineral components. The knowledge gained from this study can be used to explain the mechanisms related to irreversible processes, such as contact induced cracking and wear, and strengthen understanding of the mechanical behavior of porous mineralized tissues.
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Affiliation(s)
- Boyang Wan
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
| | - Ziyan Man
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
| | - Kai Chun Li
- Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand
| | - Michael V Swain
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
| | - Qing Li
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia.
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Zhu X, Li Y, Dong Q, Tian C, Gong J, Bai X, Ruan J, Gao J. Small Molecules Promote the Rapid Generation of Dental Epithelial Cells from Human-Induced Pluripotent Stem Cells. Int J Mol Sci 2024; 25:4138. [PMID: 38673725 PMCID: PMC11049943 DOI: 10.3390/ijms25084138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 04/28/2024] Open
Abstract
Human-induced pluripotent stem cells (hiPSCs) offer a promising source for generating dental epithelial (DE) cells. Whereas the existing differentiation protocols were time-consuming and relied heavily on growth factors, herein, we developed a three-step protocol to convert hiPSCs into DE cells in 8 days. In the first phase, hiPSCs were differentiated into non-neural ectoderm using SU5402 (an FGF signaling inhibitor). The second phase involved differentiating non-neural ectoderm into pan-placodal ectoderm and simultaneously inducing the formation of oral ectoderm (OE) using LDN193189 (a BMP signaling inhibitor) and purmorphamine (a SHH signaling activator). In the final phase, OE cells were differentiated into DE through the application of Purmorphamine, XAV939 (a WNT signaling inhibitor), and BMP4. qRT-PCR and immunostaining were performed to examine the expression of lineage-specific markers. ARS staining was performed to evaluate the formation of the mineralization nodule. The expression of PITX2, SP6, and AMBN, the emergence of mineralization nodules, and the enhanced expression of AMBN and AMELX in spheroid culture implied the generation of DE cells. This study delineates the developmental signaling pathways and uses small molecules to streamline the induction of hiPSCs into DE cells. Our findings present a simplified and quicker method for generating DE cells, contributing valuable insights for dental regeneration and dental disease research.
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Affiliation(s)
- Ximei Zhu
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China; (X.Z.); (Y.L.); (Q.D.)
- Center of Oral Public Health, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China;
| | - Yue Li
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China; (X.Z.); (Y.L.); (Q.D.)
- Center of Oral Public Health, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China;
| | - Qiannan Dong
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China; (X.Z.); (Y.L.); (Q.D.)
- Center of Oral Public Health, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China;
| | - Chunli Tian
- Center of Oral Public Health, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China;
| | - Jing Gong
- Department of Pediatric Dentistry, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China; (J.G.); (X.B.)
| | - Xiaofan Bai
- Department of Pediatric Dentistry, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China; (J.G.); (X.B.)
| | - Jianping Ruan
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China; (X.Z.); (Y.L.); (Q.D.)
- Center of Oral Public Health, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China;
| | - Jianghong Gao
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China; (X.Z.); (Y.L.); (Q.D.)
- Center of Oral Public Health, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China;
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Li Y, He P, Zheng L, Zhou X. Histone-modifying enzymes: Roles in odontogenesis and beyond. Oral Dis 2024. [PMID: 38376106 DOI: 10.1111/odi.14894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 01/25/2024] [Accepted: 01/31/2024] [Indexed: 02/21/2024]
Abstract
OBJECTIVES Odontogenesis, an intricate process initiated by epithelium-mesenchyme interaction, is meticulously regulated by a cascade of regulatory mechanisms. Epigenetic modifications, especially histone modification, have been found to exhibit spatiotemporal specificity during tooth development. However, the expression patterns and roles of enzymes associated with histone modifications have yet to be systematically explored in odontogenesis. This review aims to summarize the histone-modifying enzymes in odontogenesis and their regulation mechanism during tooth development and provide the potential theoretical basis for the clinical management and intervention of dental developmental diseases. SUBJECTS AND METHODS This study conducted a systematic search across PubMed and Web of Science databases, utilizing the keywords "odontogenesis," "histone modification," and "enzyme" for pertinent articles. RESULTS No doubt histone modification contributes extensively to odontogenesis regulation, and the disturbances in histone modifications can derange the odontogenesis process. CONCLUSION Further studies are warranted to elucidate these roles and their potential downstream effects, positioning histone modifications as a pivotal focal point for unraveling the intricacies of tooth development and regeneration.
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Affiliation(s)
- Yiting Li
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Pengcheng He
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Liwei Zheng
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Xin Zhou
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
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Chun YHP, Tan C, Villanueva O, Colley ME, Quintanilla TJ, Basiouny MS, Hartel CA, Critchfield CS, Bach SBH, Fajardo RJ, Pham CD. Overexpression of ameloblastin in secretory ameloblasts results in demarcated, hypomineralized opacities in enamel. Front Physiol 2024; 14:1233391. [PMID: 38274050 PMCID: PMC10808694 DOI: 10.3389/fphys.2023.1233391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 11/01/2023] [Indexed: 01/27/2024] Open
Abstract
Introduction: Developmental defects of the enamel manifest before tooth eruption and include amelogenesis imperfecta, a rare disease of underlying gene mutations, and molar-incisor hypomineralization (MIH), a prevalent disease in children originating from environmental and epigenetic factors. MIH enamel presents as the abnormal enamel marked by loss of translucency, demarcation between the healthy and affected enamel, and reduced mineral content. The pathophysiology of opaque, demarcated enamel lesions is not understood; however, the retention of enamel proteins in the matrix has been suggested. Ameloblastin (Ambn) is an enamel protein of the secreted calcium-binding phosphoproteins (SCPPs) critical for enamel formation. When the Ambn gene is mutated or deleted, teeth are affected by hypoplastic amelogenesis imperfecta. Methods: In this study, enamel formation in mice was analyzed when transgenic Ambn was overexpressed from the amelogenin promoter encoding full-length Ambn. Ambn was under- and overexpressed at six increasing concentrations in separate mouse lines. Results: Mice overexpressing Ambn displayed opaque enamel at low concentrations and demarcated lesions at high concentrations. The severity of enamel lesions increased starting from the inner enamel close to the dentino-enamel junction (DEJ) to span the entire width of the enamel layer in demarcated areas. Associated with the opaque enamel were 17-kDa Ambn cleavage products, a prolonged secretory stage, and a thin basement membrane in the maturation stage. Ambn accumulations found in the innermost enamel close to the DEJ and the mineralization front correlated with reduced mineral content. Demarcated enamel lesions were associated with Ambn species of 17 kDa and higher, prolonged secretory and transition stages, a thin basement membrane, and shortened maturation stages. Hypomineralized opacities were delineated against the surrounding mineralized enamel and adjacent to ameloblasts detached from the enamel surface. Inefficient Ambn cleavage, loss of contact between ameloblasts, and the altered basement membrane curtailed the endocytic activity; thus, enamel proteins remained unresorbed in the matrix. Ameloblasts have the ability to distinguish between Ambn concentration and Ambn cleavage products through finely tuned feedback mechanisms. The under- or overexpression of Ambn in murine secretory ameloblasts results in either hypoplastic amelogenesis imperfecta or hypomineralization with opaque or sharply demarcated boundaries of lesions, similar to MIH.
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Affiliation(s)
- Yong-Hee Patricia Chun
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
- Department of Cell Systems and Anatomy, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
- Department of Molecular Medicine, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Chunyan Tan
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Omar Villanueva
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Madeline E. Colley
- Department of Chemistry, University of Texas San Antonio, San Antonio, TX, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
- Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN, United States
| | - Travis J. Quintanilla
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Mohamed S. Basiouny
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Caldonia A. Hartel
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Cameron S. Critchfield
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Stephan B. H. Bach
- Department of Chemistry, University of Texas San Antonio, San Antonio, TX, United States
| | - Roberto J. Fajardo
- Department of Clinical and Applied Science Education, School of Osteopathic Medicine, University of the Incarnate Word, San Antonio, TX, United States
| | - Cong-Dat Pham
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX, United States
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